Consecutive Antibiotic Shortages Highlight Discrepancies between Microbiology and Prescribing Practices for Intra-abdominal Infections

Abstract

Piperacillin-tazobactam (TZP) is frequently used for intra-abdominal infection (IAI). Our institution experienced consecutive shortages of TZP and cefepime, providing an opportunity to review prescribing patterns and microbiology for IAI. Hospitalized adult patients treated for IAI, based on provider selection of IAI as the indication within the antibiotic order, between March 2014 and February 2018 were identified from the University of Virginia Clinical Data Repository and Infection Prevention and Control Database. Antimicrobial utilization, microbiologic data, and clinical outcomes were compared across four year-long periods: pre-shortage, TZP shortage, cefepime shortage, and post-shortage. There were 7,668 episodes of antimicrobial prescribing for an indication of IAI during the study period. Cefepime use for IAI increased 190% during the TZP shortage; meanwhile ceftriaxone use increased by only 57%. There was no increase in in-house mortality, colonization with resistant organisms, or Clostridiodes difficile infection among patients treated with IAI during the shortage periods. Among a subset of cases randomly selected for review, Pseudomonas sp. was a rare cause of IAI, but anti-pseudomonal antibiotics were commonly prescribed empirically. We observed a large increase in cefepime utilization for IAI during a TZP shortage that was not warranted based on the observed frequency of identification of Pseudomonas sp. as the causative organism in IAI, suggesting a need to revisit national guideline recommendations.

Mortality of Patients With Sepsis Administered Piperacillin-Tazobactam vs Cefepime

“…The chosen instrument was a period of piperacillin-tazobactam shortage at the University of Michigan Healthcare System from June 12, 2015, to September 18, 2016 (Figure 2). Patients admitted both before and after the shortage were included in the cohort to mitigate any bias due to temporal changes in sepsis outcomes.…”

“…Given the importance of understanding the relative efficacy of the most prevalent antibiotic regimens for critically ill patients with sepsis, we used a nationwide shortage of piperacillin-tazobactam to study differences in outcomes between these regimens as empirical treatment for sepsis . This shortage resulted in a substantial shift in antibiotic selection, which we leveraged to test the hypothesis that empirical therapy with piperacillin-tazobactam for sepsis is associated with increased 90-day mortality compared with cefepime.…”